This invention relates to electrolytic processes for etching III-V compound semiconductors, especially gallium-containing compound semiconductors.
With the expanding use of such compound semiconductors, particularly GaP and GaAs, in light emitting devices, microwave amplifiers and power sources, etc., increasing demand has been made for controllable and economical processing techniques. It is quite apparent that in order to produce discrete devices, as well as integrated circuits, some etching processes are required. Attention in prior art work has focused primarily on various chemical systems to achieve desirable etching characteristics (see, for example, U.S. Pat. No. 3,260,633, issued July 12, 1966 to H. Seiter). Electrolytic etching systems generally are more desirable, however, since etching rates may be easily controlled by controlling the amount of bias applied to the system. Several such systems have been proposed with varying degrees of success (see, for example, U.S. Pat. No. 3,418,226, issued Dec. 24, 1968 to J. C. Marinace). Most of these systems require alkali metal ions in the electrolyte which can adversely affect the electrical as well as the light emitting properties of the treated device both in the short as well as the long term.
It is therefore a primary object of the invention to provide an electrolytic process which will etch a III-V compound semiconductor controllably and, preferably, without the presence of any undesired contaminants that may degrade device properties or contribute to poor aging properties of the device.